The SLAC National Accelerator Laboratory just managed a breakthrough: it used its x-ray laser to capture detailed snapshots of photosynthesis at room temperature.
The trick was to place protein complex samples in a solution, put that on a conveyor belt, light it up with a green laser (to start the water-splitting reaction) and capture images using x-ray pulses. As those pulses are extremely fast -- just 40 femtoseconds long -- you can collect crystallization and spectroscopy data before the sample meets its untimely end.
The imagery helps illustrate chemical interactions that were previously somewhat mysterious, and it should only get better as scientists capture more images and provide additional details. Ultimately, the aim is to understand photosynthesis well enough to faithfully reproduce it. If that happens, we'll have a source of sun-based renewable energy that does not rely on conventional, not-so-efficient solar panels.
When X-rays (yellow beam) pass through a crystal (green shapes), they form an intensity pattern on a detector behind the crystal that is dominated by bright spots (dots in the background). Researchers use these so-called Bragg peaks to reconstruct atomic-resolution images of the molecules inside the crystals. In a new study at SLAC's LCLS X-ray laser, researchers used continuous diffraction -- signals found between the spots, which appear here as washed-out, continuous lines in the background -- to improve the resolution of images obtained with the conventional analysis.
Often the most difficult step in taking atomic-resolution images of biological molecules is getting them to form high-quality crystals needed for X-ray studies of their structure. Now researchers have shown they can get sharp images even with imperfect crystals using the world's brightest X-ray source at the Department of Energy's SLAC National Accelerator Laboratory.
These surprising results could in many cases make the search for better crystals obsolete and fundamentally change the way scientists study the complex biological machinery involved in photosynthesis, catalysis and many other important processes in living things. A better understanding of these processes could drive innovation in a number of areas, from clean energy production to drug development.
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